Saturday, March 26, 2016
WILL WE CAUSE THE NEXT GREAT EXTINCTION?
The primary headline in the local Honolulu Star-Advertiser yesterday blared that humans could well be stimulating the next great extinction. I don't recall, ever, this newspaper placing a scientific announcement from the University of Hawaii at the top of the front page.
Richard Zeebe, paleooceanographer at the School of Ocean and Earth Sciences, to which I also belong, published with co-authors in Nature Geoscience, an article indicating that:
...humans are releasing carbon into the atmosphere about 10 times faster than during any time in the past 66 million years.
Known as the Cretaceous-Paleogene Extinction Event (KPEE), three quarters of animal and plant life disappeared, including all non-flying dinosaurs. Those survivors evolved into the birds we see today.
While this time we are responsible, the first confirmed speculation by Luis and Walter Alvarez of that KPEE was that a 6 mile diameter asteroid crashed into the Yucatan Peninsula of Mexico, near the town of Chicxlub, the equivalent of an explosion a billion times more powerful than an Atomic-Bomb, creating a 110 mile wide crater. Well, scientists have long been mixed on that theory, as some early data indicated that dinosaurs were already mostly gone by the time the giant rock struck. However, more recently, the timing was refined, and scientists are now generally back on board. United Kingdom researchers have just begun drilling at ground zero of the impact to gain additional information.
Anyway, a little more than 10 million years after that killer asteroid, something called the Paleocene-Eocene Thermal Maximum (PETM) happened, drawing the attention of geoscientists, for there were two sudden (meaning in geologic time something on the order of 20,000 years) injections of carbon dioxide into the atmosphere, zooming up the temperature on the surface of Planet Earth at least 9 F, and perhaps as high as 14.4 F. The scary thing about all this is that we are emitting a lot more CO2 in such a short period:
Much of the above is, of course, fear-inducing, for while we might continue to be so stupid for a century at ten times the natural rate of the PETM, our planet flipped for millennia and life tolerated that sudden temperature increase, and, recovered. Humans would not have!
While the usual suspects are mentioned (volcanoe, comet, etc.), it seems that methane had a special role to play in this event, probably biogenic clathrates, my primary villain responsible for a future VENUS SYNDROME. Further, my surmisal was that global warming induced by humanity would catalyze the deepsea explosion of methane clathrates. Why is methane so bad? To quote:
According to data released by the EPA atmospheric methane (CH4) concentrations (ppb) remained between 400–800ppb (between years 600,000 BC to 1900) and since 1900 have risen to levels between 1600–1800ppb.
An upcoming posting will be on my progress with THE VENUS SYNDROME, a novel of human extinction caused by this Clathrate Gun Hypothesis. Two such episodes have been implicated: 56 million years ago during the PETM and 252 million years ago during the Permian-Triassic Extinction Event when 96% of all marine species died off.